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Pitching Fatigued: Effect of and on BB and K Rates Topic

This thread: http://www.whatifsports.com/forums/Posts.aspx?topicID=435942&page=1 inspired me to run a series of tests on pitchers with low BB and K rates and pitching them at lower fatigue fatigue levels. I'm still running these tests, but I have enough data now, that I feel I can post something. I've run three teams in an OL with the goal of having my pitchers pitch down to 80%.

I have very carefully selected pitchers that have low BB and K rates to see if their performance is effected much by fatigue (I expect their K rate to drop and BB rate to increase, but giving the low starting points of each, even a substantial % change will have a minimal real world effect; i.e., a 50% increase in BB rate for a pitcher with a 0.78 BB/9 will only see a 1.12 BB/9, which is still excellent, though significantly worse percentage-wise).

After the first test, it became clear I didn't quite have enough IP to get solid data as several of the pitchers were pitching down to the 50% range. So, I swapped out Sallee for Bernhard, Adams for Maddux and Ostrowski (and Dizzy Dean), and MIlacki for Zachary.

I'll only be focusing on the starters, Toney, and Northrup for now as I have more data on them than the others. Each has appeared on at least two teams and has at least 80 games pitched worth of data. In order of data:

That's an average of 38 more IP (14% increase) and 492 more pitches (13% increase) with a .303 OAV, 1.51 WHIP, and 4.89 ERA (with 239 uses on his performance history, his average OL slash is .278/1.32/3.43). His BB/9 increases to 1.82 when fatigued from a 1.16 RL BB/9 (a 56% increase), but it was still below his performance history average of 1.88. His K/9 decreased to a 1.33 from a RL K/9 of 2.49 (a 47% decrease), and lower than his performance history K/9 of 1.62 by 18%.

Now, in the first season of the test, I used Cleveland Stadium, in the second season I used Yankee 3, and in the third I used WIS Park. His OAV was effected more by the offensive stadiums and in the first test when he pitched as low as 60% (Had 30 starts between 60-69%) as can be seen above.

I will note, however, that his BB/9 was a 2.54 in the season he pitched down to 60%, and his OAV was .351, both SIGNIFICANTLY worse than the two seasons he pitched in the 80-85% range and his PH. With that season removed from this sample we would barely notice an effect of fatigue down to the 80% mark.

Brown was the pitcher who during the tests seemed to be the least affected by fatigue, and now I know why, he was, on average, barely pitching fatigued with an average fatigue of 88% compared to Joss's average fatigue of 80%. That said, Brown put up a slash line of .252/1.17/3.09 which compares very favorably to his PH line of .254/1.18/3.15 while throwing roughly 40 IP more than average and nearly 60 more than RL. His RL BB & K rates are 1.27 & 6.14, respectively, while his PH rates are 1.76 an 4.82. While throwing below 90% on average he regressed to 1.39 & 4.38. So, once again, the BB rate wasn't affected as much as I expected relative to PH. Though it was down from RL by a significant margin, it would appear the effect on the BB rate has more to do with the other league factors than the effect of fatigue. The K rate, however, does seem to show signs of fatigue wearing, which signifies the importance of having your ballpark and defense ready to handle more balls in play.

Maddux has one of the best RL BB/9 rates at 0.77, so I was excited to see how that would transform when fatigued, his PH BB/9 is a 1.19, which is already a huge increase, and he put up 1.22 BB/9 while pitching at an average of 84% fatigue. His K/9 goes from 6.84 RL, to 5.43 PH, to 4.52 fatigued. His OAV and ERA were both slightly off from his PH with a slash of .271/1.21/3.32 vs. .277/1.28/3.71. Which seems to correlate to his slight increase on his BB/9 vs his PH (3% increase on BB/9, 2% increase in OAV, 6% increase in WHIP and 12% in ERA).

As I noted later in this thread the last season of Maddux had another iteration in the league playing at normal fatigue (two appearances below 100%, but both above 95%). This second Maddux was playing in Safeco and put up nearly identical stats:
My fatigued Maddux:

Split Type

G

GS

W

L

SV

SVO

IP

BFP

NP

H

ER

HR

BB

SO

OAV

OBP

SLG

WHIP

ERA

Totals

38

38

21

12

0

0

292.7

1191

3928

301

107

18

25

170

.263

.282

.360

1.11

3.29

The non-fatigued Maddux:

Split Type

G

GS

W

L

SV

SVO

IP

BFP

NP

H

ER

HR

BB

SO

OAV

OBP

SLG

WHIP

ERA

Totals

69

56

12

13

0

0

263.7

1091

3563

276

88

5

23

154

.265

.286

.330

1.13

3.00

As you can see, the only real difference was the number of extra innings and batters faced by my Maddux... with the exception of HRs allowed, which seems to be the only thing affected at this level of fatigue all else being roughly equal.

Bernhard is one I expected much more from, but as one who also faced little fatigue overall (1% more fatigued than Brown 86.71 % vs. 87.68%), Bernhard fared the worst across the board. He underperformed RL and his PH by large margins in most categories: Slash lines of .253/1.22/3.14 vs. .266/1.31/3.87 and BB & K rate changes from 2.11 BB/9 and 1.65 K/9 to a 2.01 BB/9 & 1.58 K/9. His BB & K rate stats were roughly in line with his PH, but his OAV, ERA and HR numbers were elevated. Again, much of that appears to be Yankee 3 related with him serving up huge OAV and HR rates in Yankee, but outperforming his PH in both in a neutral park. Another case where I still need more data, and more fatigue...

As may be plainly obvious, despite my best attempts, I struggled to get Toney to experience much fatigue. Down the stretch in this last season I started him in a one man rotation (his 6 starts). Still, he never dropped below 100% in season 3, and barely did in season 2. We're not going to gather much from his data yet, but anyway his PH BB/9 & K/9 of 1.56 and 2.42 were 1.26 & 1.77 in my three leagues, so maybe his K rate was affected some by the 84% in league one, but he still dominated in the BB/9 category, not even having his worst rate in his most fatigued season.

With the data from Season 4, Toney had his 2nd highest level of fatigue, but also put up his best numbers... showing the difference both ballpark selection and sample size put into play. Will be really interested in the additional data from the currently running league with the same ballpark, but with a defense in play as well.

Even though he had one full season without any real fatigue (one appearance at 97%), he had two seasons with an average appearance below 83%, which works out to an average appearance of just under 88%. He also has the smallest sample size in terms of IP, but is the furthest from his RL & PH stats. He finished my sample with a 1.07 BB/9 and 0.82 K/9 vs PH rates of 1.77 and 1.05. Once again besting the BB rate but failing to live up to the K rate. His triple slash is significantly worse than the PH .242/1.13/2.71 with his .267/1.21/3.42 and he he gave up an average of three times the HRs... granted, most of that difference comes to the two + hit and HR stadiums...

Now with the 4th season added in, his numbers are starting to look more Northrop like, while his fatigue levels decreased as he went from an 88% average fatigue to an 86.75% average fatigue. His 4th season was his best statistically, while it was also one of the more fatigued seasons (82.95%).

Seems to show that if you control for the two main variables (HRs and hits) and start with low BB numbers (K's seem to be unimportant, except for maybe increasing the number of pitches the pitcher can throw) fatigue down to the low 80's is negligible at best.

I goofed initially by putting them in +1B and +HR ballparks for the first two tests. It has skewed the OAV and HR results, so I need to run a few more to get better data on those stats, the BB and K rates, however, are mostly what this was about, so they remain unaffected.

That said, after compiling these stats its clear we need a few more seasons of data. I'll run out these same staffs in WIS Park a few more times while saving the data to add it to what's already been collected here so far.

However, even with this limited data, it seems that the BB rate isn't affected as much as I would have guessed by fatigue into the 80s, though it definitely balloons once you reach the 60s, likewise for OAV. K rates do seem to be affected even at low levels of fatigue, and so long as you plan accordingly with pitcher friendly ballparks and a defense that can handle extra balls in play, these low levels of fatigue seem to be very manageable, if not exploitable.

Also, I should note, that the fatigue percentage listed for each pitcher is not their final fatigue %, but the average fatigue % for each appearance. In the first season test Addie Joss finished at a 59% fatigue, and there were a few more in season 1 that went into the 50s, while in the other test seasons I had a few pitchers who barely dropped below 100, but most of the others pitchers/tests finished between 77-84%.

great piece just4me im new to wis but i love numbers and am hooked. reading your piece has convinced me of one thing ive been wanting to try. I really like 05 joss in the polo grounds as a number 3 starter he has winning over twenty but i have to keep his pitch count at 85 so he stays at 100% i am gonna raise that to 110 and let his fatigue go into the eightys and see what happens thanks